Sulfonamide based polymers for copper electroplating

ABSTRACT

Sulfonamide based polymers are reaction products of sulfonamides and epoxides. The polymers may be used as levelers in copper electroplating baths, to provide good throwing power. Such reaction products may plate copper or copper alloys with good surface properties and good physical reliability.

The present application is a divisional application of co-pendingapplication Ser. No. 14/585,227, filed Dec. 30, 2014.

FIELD OF THE INVENTION

The present invention is directed to sulfonamide based polymers forcopper electroplating. More specifically, the present invention isdirected to sulfonamide based polymers for copper electroplating wherethe sulfonamide based polymers are reaction products of sulfonamide orsalts thereof, and an epoxide.

BACKGROUND OF THE INVENTION

Methods for electroplating articles with metal coatings generallyinvolve passing a current between two electrodes in a plating solutionwhere one of the electrodes is the article to be plated. A typical acidcopper plating solution includes dissolved copper, usually coppersulfate, an acid electrolyte such as sulfuric acid in an amountsufficient to impart conductivity to the bath, a source of halide, andproprietary additives to improve the uniformity of the plating and thequality of the metal deposit. Such additives include levelers,accelerators and suppressors, among others.

Electrolytic copper plating solutions are used in a variety ofindustrial applications, such as decorative and anticorrosion coatings,as well as in the electronics industry, particularly for the fabricationof printed circuit boards and semiconductors. For circuit boardfabrication, typically, copper is electroplated over selected portionsof the surface of a printed circuit board, into blind vias and trenchesand on the walls of through-holes passing between the surfaces of thecircuit board base material. The exposed surfaces of blind vias,trenches and through-holes, i.e. the walls and the floor, are first madeconductive, such as by electroless metallization, before copper iselectroplated on surfaces of these apertures. Plated through-holesprovide a conductive pathway from one board surface to the other. Viasand trenches provide conductive pathways between circuit board innerlayers. For semiconductor fabrication, copper is electroplated over asurface of a wafer containing a variety of features such as vias,trenches or combinations thereof. The vias and trenches are metallizedto provide conductivity between various layers of the semiconductordevice.

It is well known in certain areas of plating, such as in electroplatingof printed circuit boards (“PCBs”), that the use of levelers in theelectroplating bath can be crucial in achieving a uniform metal depositon a substrate surface. Electroplating a substrate having irregulartopography can pose difficulties. During electroplating a voltage droptypically occurs within apertures in a surface, which can result in anuneven metal deposit between the surface and the apertures.Electroplating irregularities are exacerbated where the voltage drop isrelatively extreme, that is, where the apertures are narrow and tall.Consequently, depositing a metal layer of substantially uniformthickness is frequently a challenging step in the manufacture ofelectronic devices. Leveling agents are often used in copper platingbaths to provide substantially uniform, or level, copper layers inelectronic devices.

The trend of portability combined with increased functionality ofelectronic devices has driven the miniaturization of PCBs. Conventionalmultilayer PCBs with through-hole interconnects are not always apractical solution. Alternative approaches for high densityinterconnects have been developed, such as sequential build uptechnologies, which utilize blind vias. One of the objectives inprocesses that use blind vias is the maximizing of via filling whileminimizing thickness variation in the copper deposit between the viasand the substrate surface. This is particularly challenging when the PCBcontains both through-holes and blind vias.

Leveling agents are used in copper plating baths to level the depositacross the substrate surface and to improve the throwing power of theelectroplating bath. Throwing power is defined as the ratio of thethrough-hole center copper deposit thickness to its thickness at thesurface. Newer PCBs are being manufactured that contain boththrough-holes and blind vias. Current bath additives, in particularcurrent leveling agents, do not always provide level copper depositsbetween the substrate surface and filled through-holes and blind vias.Via fill is characterized by the difference in height between the copperin the filled via and the surface.

Another problem encountered in copper plating is the formation ofnodules on the copper deposit. Nodules are believed to be crystals ofthe metal being plated and grow out of the plated surface. Nodules mayrange in diameter from less than 1 micron to as large as severalmillimeters. Nodules are undesirable for a variety of electrical,mechanical, and cosmetic reasons. For example, nodules are readilydetached and carried by cooling air flows into electronic assemblies,both within and external to electronic article housings, where they maycause short-circuit failure. Therefore, the nodules have to be removedbefore the plated substrates are assembled into electronic articles.Conventional methods of removing the nodules involve laser inspection ofeach copper plated substrate followed by manual removal of the nodulesby workers using microscopes. Such conventional methods leave room forworker error and are inefficient.

Accordingly, there remains a need in the art for leveling agents for usein copper electroplating baths for the manufacture of PCBs that providelevel copper deposits while bolstering the throwing power of the bathand reducing nodules.

SUMMARY OF THE INVENTION

A reaction product includes one or more sulfonamides or salts thereof,and one or more epoxides.

A composition includes one or more sources of copper ions, electrolyteand a reaction product including one or more sulfonamides or saltsthereof, and one or more epoxides.

A method includes: providing a substrate; providing a compositionincluding one or more sources of copper ions, electrolyte and a reactionproduct including one or more sulfonamides or salts thereof, and one ormore epoxides; contacting a substrate with the composition; applying acurrent to the substrate and the composition; and depositing copper orcopper alloy on the substrate.

The reaction products provide copper layers having a substantially levelsurface across a substrate, even on substrates having small features andon substrates having a variety of feature sizes. The plating methodseffectively deposit copper on substrates and in blind vias andthrough-holes such that the copper plating compositions may have goodthrowing power. In addition, copper deposits may have good physicalreliability in response to thermal shock stress tests and reducednodules.

DETAILED DESCRIPTION OF THE INVENTION

As used throughout this specification the following abbreviations shallhave the following meanings unless the context clearly indicatesotherwise: A=amperes; A/dm²=amperes per square decimeter; ° C.=degreesCentigrade; g=gram; ppm=parts per million; L=liter,μm=micron=micrometer; mm=millimeters; cm=centimeters; DI=deionized;mL=milliliter; mol=moles; mmol=millimoles; Mw=weight average molecularweight; Mn=number average molecular weight; and PEG=polyethylene glycolmoiety. All numerical ranges are inclusive and combinable in any order,except where it is clear that such numerical ranges are constrained toadd up to 100%.

As used throughout the specification, “feature” refers to the geometrieson a substrate. “Aperture” refers to recessed features includingthrough-holes and blind vias. As used throughout this specification, theterm “plating” refers to metal electroplating. “Deposition” and“plating” are used interchangeably throughout this specification.“Leveler” refers to an organic polymer compound or salt thereof that iscapable of providing a substantially level or planar metal layer. Theterms “leveler” and “leveling agent” are used interchangeably throughoutthis specification. “Accelerator” refers to an organic additive thatincreases the plating rate of the electroplating bath and may functionas a brightener. “Suppressor” refers to an organic additive thatsuppresses the plating rate of a metal during electroplating. The terms“printed circuit boards” and “printed wiring boards” are usedinterchangeably throughout this specification. The term “moiety” means apart of a molecule or polymer that may include either whole functionalgroups or parts of functional groups as substructures. The terms“moiety” and “group” are used interchangeably throughout thespecification. The term “monomer” and “compound” are usedinterchangeably in the specification. A “polymer” is a molecule whichincludes two or more mers. “monomer” means a single mer or smallmolecule or compound of which two or more compose a polymer. The term“amine” in the context of the present application refers to nitrogencontaining compounds which exclude the sulfonamide moiety. The “----”dashed line in chemical structures means an optional double bond. Thearticles “a” and “an” refer to the singular and the plural.

Polymers are reaction products of one or more sulfonamides or saltsthereof, and one or more epoxides. Optionally, one or more amines may beincluded as a third monomer, thus the polymers may include one or moresulfonamides or salts thereof, one or more epoxides and one or moreamines. The reaction products may be used in copper electroplatingcompositions to plate copper deposits on substrates that may includeblind vias, through-holes or combinations thereof. The copperelectroplating compositions have good throwing power and the copperdeposits have good physical reliability in response to thermal shockstress tests and reduced nodules.

Sulfonamides include compounds having a general formula:

where R is linear or branched, substituted or unsubstituted alkyl,linear or branched, substituted or unsubstituted alkenyl, linear orbranched, substituted or unsubstituted alkynyl, or substituted orunsubstituted aryl and R′ is hydrogen, linear or branched, substitutedor unsubstituted alkyl, linear or branched, substituted or unsubstitutedalkenyl, linear or branched substituted or unsubstituted alkynyl orsubstituted or unsubstituted aryl. Substituent groups include, but arenot limited to halogen such as chlorine, bromine, fluorine and iodine,linear or branched halo(C₁-C₁₀)alkyl, hydroxyl, hydroxylalkyl, amine,linear or branched alkylamine, linear or branched alkyl and linear orbranched alkoxy.

Preferably, R is substituted or unsubstituted phenyl, substituted orunsubstituted naphthyl, substituted and unsubstituted biphenyl,substituted or unsubstituted (C₅-C₆)heteroaryl such as thienyl, pyridyl,thazolyl, oxazolyl, imidazolyl, pyrazolyl, piperidinyl, pyrrolidinyl andmorpholinyl, linear or branched, substituted or unsubstituted(C₁-C₁₀)alkyl, linear or branched, substituted or unsubstituted(C₂-C₁₀)alkenyl, linear or branched, substituted or unsubstituted(C₂-C₁₀)alkynyl. Preferably R′ is hydrogen, substituted or unsubstitutedphenyl, linear or branched, substituted or unsubstituted (C₁-C₁₀)alkyl,linear or branched, substituted or unsubstituted (C₂-C₁₀)alkenyl, linearor branched, substituted or unsubstituted (C₂-C₁₀)alkynyl, or linear orbranched, substituted or unsubstituted (C₁-C₁₀)alkoxy. Substituentgroups include, but are not limited to halogen, linear or branchedhalo(C₁-C₁₀)alkyl, hydroxyl, linear or branched hydroxyl(C₁-C₁₀)alkyland linear or branched (C₁-C₁₀)alkylamine.

More preferably R is substituted or unsubstituted phenyl or substitutedor unsubstituted naphthyl, substituted or unsubstituted(C₅-C₆)heteroaryl and R′ is hydrogen, linear or branched, substituted orunsubstituted (C₁-C₅)alkyl, linear or branched, substituted orunsubstituted (C₁-C₁₀)alkoxy and linear or branched, substituted orunsubstituted (C₁-C₁₀)alkylamine. Substituent groups include, but arenot limited to halogen, hydroxyl, linear or branchedhydroxyl(C₁-C₅)alkyl, amine and linear or branched (C₁-C₅)alkylamine.

Sulfonamides also include those having a formula:

where R is as defined above and R″ is substituted or unsubstitutedarylene, linear or branched (C₁-C₁₀)alkylene or a moiety having thefollowing structure:

where R₁, R₂, R₃ and R₄ are the same or different and are chosen fromhydrogen and linear or branched (C₁-C₅)alkyl, v, w and x are the same ordifferent and are integers 1-10, preferably 1-5, more preferably 1-3.Substituents on the arylene include, but are not limited to hydroxyl,linear or branched hydroxyl(C₁-C₅)alkyl, —NO₂, primary or secondaryamine, linear or branched (C₁-C₅)alkylamine.

Salts of the foregoing sulfonamides include, but are not limited toalkali metal salts such as sodium and potassium salts. When salts areused, preferably, sodium salts are used. Sulfonamides and salts ofsulfonamides may be mixed together to form the reaction products.

Epoxide compounds include those having 1 or more epoxide moieties,preferably 2 or more joined together by a linkage, more preferably 2 to4 epoxide moieties are present. Preferably, such epoxides include, butare not limited to compounds having formula:

where Y, R₅ and R₆ may be the same or different and are chosen fromhydrogen and (C₁-C₄)alkyl, X is halogen, such as chlorine, bromine,fluorine and iodine, A=OR₁₀ or R₁₁; R₁₀═((CR₁₂R₁₃)_(m)O), (aryl-O)_(p),CR₁₂R₁₃—Z—CR₁₂CR₁₃, or OZ′_(t)O, R₁₁═(CH₂)_(y), B is (C₅-C₁₂)cycloalkyl,Z=a 5- or 6-membered ring, Z′ is R₁₄OArOR₁₄, (R₁₅O)_(b)Ar(OR₁₅), or(R₁₅O)_(b), Cy(OR₁₅), Cy=(C₅-C₁₂)cycloalkyl; each R₁₂ and R₁₃ areindependently chosen from hydrogen, methyl, or hydroxyl, each R₁₄represents (C₁-C₈)alkyl, each R₁₅ represents a (C₂-C₆)alkyleneoxy; R₇ isa hydrogen atom, a formyl group, or one or two glycidyl ether groupseach optionally containing a carbonyl group constituted by C₄-C₈ andC₂-C₄, R₈ is a hydrogen atom, a methyl group or an ethyl group, and R₉is a hydrogen atom, a formyl group, or one or two glycidyl ether groupseach optionally containing a carbonyl group constituted by C₄-C₈ andC₂-C₄, each b=1-10, m=1-6, n=1-4, p=1-6, t=1-4 and y=0-6. R₅ and R₆ arepreferably independently chosen from hydrogen and (C₁-C₂)alkyl. When R₅and R₆ are not joined to form a cyclic compound, it is preferred that R₅and R₆ are both hydrogen. When R₅ and R₆ are joined to form a cycliccompound, it is preferred that A is R₁₁ or a chemical bond and that a(C₈-C₁₀)carbocyclic ring is formed. It is preferred that m=2-4. Phenyl-Ois the preferred aryl-O group for R₁₀. It is preferred that p=1-4, morepreferably 1-3, and still more preferably 1-2. Z is preferably a 5- or6-membered carbocyclic ring and, more preferably, Z is a 6-memberedcarbocyclic ring. Preferably, y=0-4, and more preferably, 1-4. WhenA=R₁₁ and y=0, then A is a chemical bond. Preferably, Z′=R₁₄OArOR₁₄ or(R₁₅O)_(b)Ar(OR₁₅). Each R₁₄ is preferably (C₁-C₆)alkyl and morepreferably (C₁-C₄)alkyl. Each R₁₅ is preferably (C₂-C₄)alkyleneoxy. Itis preferred that t=1-2. Preferably, b=1-8, more preferably, 1-6, andmost preferably, 1-4. Each Ar group may be substituted with one or moresubstituent groups which include, but are not limited to, (C₁-C₄)alkyl,(C₁-C₄)alkoxy or halogen. Preferably Ar is (C₆-C₁₅)aryl. Exemplary arylgroups are phenyl, methylphenyl, naphthyl, pyridinyl, bisphenylmethyland 2,2-bisphenylpropyl. Preferably Cy is (C₆-C₁₅)cycloalkyl. The(C₅-C₁₂)cycloalkyl groups for B may be monocyclic, spirocyclic, fused orbicyclic groups. Preferably B is a (C₈-C₁₀)cycloalkyl, more preferably,cyclooctyl. Preferably, R₇ and R₉ are independently a hydrogen atom or aglycidyl ether group and R₈ is a hydrogen atom or an ethyl group.

Compounds of formula (IV) include, but are not limited toepichlorohydrin and epibromohydrin.

Compounds of formula (V) include, but are not limited to, 1,4-butanedioldiglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycoldiglycidyl ether, triethylene glycol diglycidyl ether, glyceroldiglycidyl ether, neopentyl glycol diglycidyl ether, propylene glycoldiglycidyl ether, dipropylene glycol diglycidyl ether andpoly(propyleneglycol)diglycidyl ether.

Compounds of formula (VI) include, but are not limited to,dicyclopentadiene dioxide and 1,2,5,6-diepoxycyclooctane.

Compounds of formula (VII) include, but are not limited to, glycerintriglycidyl ether, trimethylolpropanetriglycidyl ether, diglyceroltetraglycidyl ether, erythritol tetraglycidyl ether, arabinosetetraglycidyl ether, triglycerol pentaglycidyl ether, fructosepentaglycidyl ether, xylitol pentaglycidyl ether, tetraglycerolhexaglycidyl ether, and sorbitol hexaglycidyl ether.

Optionally, but preferably, one or more amines may be included asmonomers. Such amines include, but are not limited to primary, secondaryand hydroxyl amines. Such amines may have the following structure:

where R₁₆ and R₁₇ are the same or different and include, but are notlimited to hydrogen, linear or branched (C₁-C₁₀)alkyl, linear orbranched hydroxyl(C₁-C₁₀)alkyl, or substituted or unsubstituted aryl.Substituent groups on the aryl include, but are not limited to hydroxyl,hydroxyl(C₁-C₁₀)alkyl, linear or branched (C₁-C₁₀)alkyl, amine,(C₁-C₁₀)alkylamine and —NO₂. Preferably R₁₆ and R₁₇ are different andare hydrogen, hydroxyl or linear or branched hydroxyl(C₁-C₁₀)alkyl, morepreferably, R₁₆ and R₁₇ are different and are hydrogen or linear orbranched hydroxyl(C₁-C₅)alkyl.

Amines also include polyamines. Such polyamines include but are notlimited to compounds having general formula:

where R₁₉ is a —(CH₂—CH₂)_(i)—,—(CH₂—CH₂)_(i)—(NH—R₂₁—NH)_(k)—(CH₂—CH₂)_(i)—,—(CH₂—CH₂)_(i)—(O—R₂₂—O)_(r)—(CH₂)_(i), a substituted or unsubstituted(C₆-C₁₈)aryl, where R₂₁ is —(CH₂—CH₂)_(i)—, or

where i, k and r are independently integers of one or greater,preferably from 1 to 10; R₁₈ and R₂₀ are independently hydrogen, linearor branched (C₁-C₁₂)alkyl or substituted or unsubstituted (C₆-C₁₈)aryl,where when R₁₈ and R₂₀ are (C₁-C₁₂)alkyl, they may be taken togetherwith all of the atoms in the group to form a ring. R₂₂ is linear orbranched (C₂-C₁₀)alkyl. Substituents on the aryl groups include, but arenot limited to linear or branched (C₁-C₁₂)alkyl, linear or branchedhydroxy(C₁-C₁₂)alkyl, or hydroxyl.

Amines also include heterocyclic nitrogen compounds which may bearomatic or non-aromatic. Preferably the amines are heterocyclicnitrogen compounds. Heterocyclic nitrogen compounds include, but are notlimited to, imidazoles, triazoles, tetrazoles, pyrazines,benzimidazoles, benzotriazoles, purines, piperazines, pyridazines,pyrazoles, triazines, tetrazines, pyrimidines, benzoxazoles, oxazoles,pyridines, morpholines, pyrrolidines, pyrroles, quinolines,isoquinolines and benzothiazoles. The heterocyclic nitrogen compoundsmay have one or more substituent groups joined to the rings. Suchsubstituent groups include, but are not limited to linear or branched,substituted or unsubstituted alkyl, hydroxyl, nitro or nitroalkyl,nitroso or nitrosoalkyl, carbonyl, mercapto or mercaptoalkyl, linear orbranched hydroxyalkyl, carboxyl, linear or branched carboxyalkyl, linearor branched alkoxy, substituted or unsubstituted aryl, linear orbranched, substituted or unsubstituted arylalkyl, linear or branched,substituted or unsubstituted aminealkyl, linear or branched, substitutedor unsubstituted amine. Preferably the heterocyclic nitrogen compoundshave an a hydrogen on a nitrogen of the ring.

Heterocyclic nitrogen compounds may have the following generalstructure:

where Q₁-Q₄ may be nitrogen, oxygen, carbon, or sulfur with the provisothat at least one of the Q₁-Q₄ is nitrogen, and that only one of theQ₁-Q₄ may be oxygen or sulfur at any instance. When sulfur or oxygen isin the ring, sulfur or oxygen is at Q₄. Preferably, the ring has one tothree nitrogen atoms, more preferably one or two nitrogen atoms. Thecarbon atoms and nitrogen atoms may be substituted or unsubstituted.Substituents on carbon atoms and nitrogen atoms, including R₂₃, includebut are not limited to, linear or branched, substituted or unsubstituted(C₁-C₁₀)alkyl; hydroxyl; linear or branched alkoxy; linear or branched,substituted or unsubstituted hydroxy(C₁-C₁₀)alkyl; linear or branched,substituted or unsubstituted alkoxy(C₁-C₁₀)alkyl; linear or branched,substituted or unsubstituted carboxy(C₁-C₁₀)alkyl; linear or branched,substituted or unsubstituted amine(C₁-C₁₀)alkyl; substituted orunsubstituted aryl; linear or branched, substituted or unsubstitutedaryl(C₁-C₁₀)alkyl; and substituted or unsubstituted amine. When Q₁ iscarbon, R₂₃ and the substituent on Q₁ may be taken together with all oftheir atoms to form a six-membered carbon or heterocyclic aromatic fusedring with the ring of structure (X).

Heterocyclic nitrogen compounds where R₂₃ and the substituent on Q₁ whenQ₁ is carbon are taken together to form a six-membered aromatic fusedring may have the following general structure:

where Q₂-Q₄ are as defined above and Q₅-Q₈ may be carbon or nitrogenatoms with the proviso that only two of Q₅-Q₈ may be nitrogen at aninstance. The carbon and nitrogen atoms for the rings may be substitutedor unsubstituted. Substituents include but are not limited to, hydroxyl;linear or branched alkoxy; linear or branched, substituted orunsubstituted hydroxy(C₁-C₁₀)alkyl; linear or branched, substituted orunsubstituted alkoxy(C₁-C₁₀)alkyl; linear or branched, substituted orunsubstituted carboxy(C₁-C₁₀)alkyl; linear or branched, substituted orunsubstituted aryl; linear or branched, substituted or unsubstitutedaryl(C₁-C₁₀)alkyl; and substituted or unsubstituted amine. Suchcompounds include, but are not limited to benzimidazoles,benzotriazoles, benzoxazoles, benzothiazoles, and purines. Preferably,such compounds are benzimidazoles.

Heterocyclic nitrogen compounds also include those having a generalstructure:

where Q₉-Q₁₄ may be nitrogen, carbon or oxygen with the proviso that atleast one of Q₉-Q₁₄ is nitrogen and there are no more than four nitrogenatoms in the ring. The carbon atoms and nitrogen atoms in the ring maybe substituted or unsubstituted. Substituent groups may be the same ordifferent and include, but are not limited to, those substituent groupsdescribed for Q₁-Q₈, above. When oxygen is present in the ring, only oneof Q₉-Q₁₄ is oxygen at any instance. Heterocyclic nitrogen compounds ofstructure (XII) may be aromatic or non-aromatic heterocyclic nitrogencompounds.

The order of addition of monomers to a reaction vessel may vary,however, preferably, one or more sulfonamides or salts thereof and oneor more amines are dissolved in ethanol at room temperature withdropwise addition of one or more epoxides. The temperature of theheating bath is then increased from room temperature to 110° C. Heatingwith stirring is done for 2 hours to 4 hours. All of the solvent isremoved at 110° C. The reaction mixture is still kept at 110° C. in neatstate for additional 0.5 hours to 1.5 hours. The amounts for eachcomponent may vary but, in general, sufficient amount of each reactantis added to provide a product where the molar ratio of the moieties ofthe sulfonamide to the epoxy ranges from 0.5-5:0.5-5, preferably1-4:1-4. When one or more amines are included, the molar ratio ofsulfonamide to epoxy to amine ranges from 0.5-5:0.1-5:0.01-5 based onmonomer molar ratios, preferably from 1-3:1-3:1-3. Preferably thereaction products consist of one or more sulfonamides or salts thereofand one or more epoxides. More preferably the reaction products consistof one or more sulfonamides or salts thereof, one or more amines and oneor more epoxides.

The plating compositions and methods which include one or more of thereaction products are useful in providing a substantially level platedcopper layer on a substrate, such as a printed circuit board orsemiconductor chip. Also, the plating compositions and methods areuseful in filling apertures in a substrate with copper. The copperdeposits may have good throwing power and good physical reliability inresponse to thermal shock stress tests. Also, the copper deposits havereduced nodules.

Any substrate upon which copper can be electroplated may be used as asubstrate with the metal plating compositions containing the reactionproducts. Such substrates include, but are not limited to printed wiringboards, integrated circuits, semiconductor packages, lead frames andinterconnects. An integrated circuit substrate may be a wafer used in adual damascene manufacturing process. Such substrates typically containa number of features, particularly apertures, having a variety of sizes.Through-holes in a PCB may have a variety of diameters, such as from 50μm to 350 μm in diameter. Such through-holes may vary in depth, such asfrom 0.8 mm to 10 mm. PCBs may contain blind vias having a wide varietyof sizes, such as up to 200 μm diameter and 150 μm depth, or greater.

Copper plating compositions contain a source of copper ions, anelectrolyte, and a leveling agent, where the leveling agent is areaction product of one or more sulfonamides or salts thereof, one ormore epoxides and optionally one or more amines. The copper platingcompositions may contain a source of halide ions, an accelerator orbrightener and a suppressor. In addition to copper, the platingcompositions may include one or more alloying metals such as tin forplating copper/tin alloys.

Suitable copper ion sources are copper salts and include withoutlimitation: copper sulfate; copper halides such as copper chloride;copper acetate; copper nitrate; copper tetrafluoroborate; copperalkylsulfonates; copper aryl sulfonates; copper sulfamate; copperperchlorate and copper gluconate. Exemplary copper alkane sulfonatesinclude copper (C₁-C₆)alkane sulfonate and more preferably copper(C₁-C₃)alkane sulfonate. Preferred copper alkane sulfonates are coppermethanesulfonate, copper ethanesulfonate and copper propanesulfonate.Exemplary copper arylsulfonates include, without limitation, copperbenzenesulfonate and copper p-toluenesulfonate. Mixtures of copper ionsources may be used. One or more salts of metal ions other than copperions may be added to the present electroplating baths. Typically, thecopper salt is present in an amount sufficient to provide an amount ofcopper metal of 10 to 400 g/L of plating solution.

Suitable tin compounds include, but are not limited to salts, such astin halides, tin sulfates, tin alkane sulfonate such as tin methanesulfonate, tin aryl sulfonate such as tin benzenesulfonate and tinp-toluenesulfonate. The amount of tin compound in these electrolytecompositions is typically an amount that provides a tin content in therange of 5 to 150 g/L. Mixtures of tin compounds may be used in anamount as described above.

The electrolyte useful in the present invention may be alkaline oracidic. Preferably the electrolyte is acidic. Preferably, the pH of theelectrolyte is ≦2. Suitable acidic electrolytes include, but are notlimited to, sulfuric acid, acetic acid, fluoroboric acid, alkanesulfonicacids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonicacid and trifluoromethane sulfonic acid, aryl sulfonic acids such asbenzenesulfonic acid, p-toluenesulfonic acid, sulfamic acid,hydrochloric acid, hydrobromic acid, perchloric acid, nitric acid,chromic acid and phosphoric acid. Mixtures of acids may be used in thepresent metal plating baths. Preferred acids include sulfuric acid,methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid,hydrochloric acid and mixtures thereof. The acids may be present in anamount in the range of 1 to 400 g/L. Electrolytes are generallycommercially available from a variety of sources and may be used withoutfurther purification.

Such electrolytes may optionally contain a source of halide ions.Typically chloride ions are used. Exemplary chloride ion sources includecopper chloride, tin chloride, sodium chloride, potassium chloride andhydrochloric acid. A wide range of halide ion concentrations may be usedin the present invention. Typically, the halide ion concentration is inthe range of 0 to 100 ppm based on the plating bath. Such halide ionsources are generally commercially available and may be used withoutfurther purification.

The plating compositions typically contain an accelerator. Anyaccelerators (also referred to as brightening agents) are suitable foruse in the present invention. Such accelerators are well-known to thoseskilled in the art. Accelerators include, but are not limited to,N,N-dimethyl-dithiocarbamic acid-(3-sulfopropyl)ester;3-mercapto-propylsulfonic acid-(3-sulfopropyl)ester;3-mercapto-propylsulfonic acid sodium salt; carbonic acid,dithio-O-ethylester-S-ester with 3-mercapto-1-propane sulfonic acidpotassium salt; bis-sulfopropyl disulfide; bis-(sodiumsulfopropyl)-disulfide; 3-(benzothiazolyl-S-thio)propyl sulfonic acidsodium salt; pyridinium propyl sulfobetaine;1-sodium-3-mercaptopropane-1-sulfonate; N,N-dimethyl-dithiocarbamicacid-(3-sulfoethyl)ester; 3-mercapto-ethyl propylsulfonicacid-(3-sulfoethyl)ester; 3-mercapto-ethylsulfonic acid sodium salt;carbonic acid-dithio-O-ethylester-S-ester with 3-mercapto-1-ethanesulfonic acid potassium salt; bis-sulfoethyl disulfide;3-(benzothiazolyl-S-thio)ethyl sulfonic acid sodium salt; pyridiniumethyl sulfobetaine; and 1-sodium-3-mercaptoethane-1-sulfonate.Accelerators may be used in a variety of amounts. In general,accelerators are used in an amount in a range of 0.1 ppm to 1000 ppm.

Any compound capable of suppressing the metal plating rate may be usedas a suppressor in the present electroplating compositions. Suitablesuppressors include, but are not limited to, polypropylene glycolcopolymers and polyethylene glycol copolymers, including ethyleneoxide-propylene oxide (“EO/PO”) copolymers and butyl alcohol-ethyleneoxide-propylene oxide copolymers. Suitable butyl alcohol-ethyleneoxide-propylene oxide copolymers are those having a weight averagemolecular weight of 100 to 100,000, preferably 500 to 10,000. When suchsuppressors are used, they are typically present in an amount in therange of 1 to 10,000 ppm based on the weight of the composition, andmore typically from 5 to 10,000 ppm. The leveling agents of the presentinvention may also possess functionality capable of acting assuppressors.

In general, the reaction products have a number average molecular weight(Mn) of 200 to 100,000, typically from 300 to 50,000, preferably from500 to 30,000, although reaction products having other Mn values may beused. Such reaction products may have a weight average molecular weight(Mw) value in the range of 1000 to 50,000, typically from 5000 to30,000, although other Mw values may be used.

The amount of the reaction product or leveling agent used in the metalelectroplating compositions depends upon the particular leveling agentsselected, the concentration of the copper and any alloying metal ions inthe electroplating composition, the particular electrolyte used, theconcentration of the electrolyte and the current density applied. Ingeneral, the total amount of the leveling agent in the electroplatingcomposition ranges from 0.01 ppm to 500 ppm, preferably from 0.1 ppm to250 ppm, most preferably from 0.5 ppm to 100 ppm, based on the totalweight of the plating composition, although greater or lesser amountsmay be used.

The electroplating compositions may be prepared by combining thecomponents in any order. It is preferred that the inorganic componentssuch as source of metal ions, water, electrolyte and optional halide ionsource are first added to the bath vessel, followed by the organiccomponents such as leveling agent, accelerator, suppressor, and anyother organic component.

The electroplating compositions may optionally contain at least oneadditional leveling agent. Such additional leveling agents may beanother leveling agent of the present invention, or alternatively, maybe any conventional leveling agent. Suitable conventional levelingagents that can be used in combination with the present leveling agentsinclude, without limitations, those disclosed in U.S. Pat. No. 6,610,192to Step et al., U.S. Pat. No. 7,128,822 to Wang et al., U.S. Pat. No.7,374,652 to Hayashi et al. and U.S. Pat. No. 6,800,188 to Hagiwara etal. Such combination of leveling agents may be used to tailor thecharacteristics of the plating bath, including leveling ability andthrowing power.

Typically, the plating compositions may be used at any temperature from10 to 65° C. or higher. Preferably, the temperature of the platingcomposition is from 10 to 35° C. and more preferably from 15 to 30° C.

In general, the metal electroplating compositions are agitated duringuse. Any suitable agitation method may be used and such methods arewell-known in the art. Suitable agitation methods include, but are notlimited to: air sparging, work piece agitation, and impingement.

Typically, a substrate is electroplated by contacting the substrate withthe plating composition. The substrate typically functions as thecathode. The plating composition contains an anode, which may be solubleor insoluble. Potential is typically applied to the electrodes.Sufficient current density is applied and plating performed for a periodof time sufficient to deposit a metal layer having a desired thicknesson the substrate as well as to fill blind vias, trenches andthrough-holes, or to conformally plate through-holes. Current densitiesmay range from 0.05 to 10 A/dm², although higher and lower currentdensities may be used. The specific current density depends in part uponthe substrate to be plated, the composition of the plating bath, and thedesired surface metal thickness. Such current density choice is withinthe abilities of those skilled in the art.

Substantially level metal deposits are obtained on a PCB. Through-holes,blind vias or combinations thereof in the PCB are substantially filledor through-holes are conformally plated with desirable throwing power. Afurther advantage of the present invention is that a wide range ofapertures and aperture sizes may be filled or conformally plated withdesirable throwing power.

Throwing power is defined as the ratio of the average thickness of themetal plated in the center of a through-hole compared to the averagethickness of the metal plated at the surface of the PCB sample and isreported as a percentage. The higher the throwing power, the better theplating composition is able to conformally plate the through-hole. Metalplating compositions of the present invention may have a throwing powerof ≧65%, preferably ≧70%.

The reaction products provide copper layers having a substantially levelsurface across a substrate, even on substrates having small features andon substrates having a variety of feature sizes. The plating methodseffectively deposit copper and copper alloys on substrates and in blindvias and through-holes such that the copper plating compositions mayhave good throwing power. In addition, copper deposits may have goodphysical reliability in response to thermal shock stress tests andreduced nodules.

The following examples are intended to further illustrate the inventionbut are not intended to limit its scope.

Example 1

To a 100 mL round bottom three-neck flask equipped with a condenser anda magnetic stirrer, 5 mmol benzenesulfonamide was added followed byaddition of a solution of 5 mmol poly(ethyleneglycol)diglycidyl ether(Mn 526) in 30 mL of ethanol. 5 mg K₂CO₃ was then added into thereaction mixture. The mixture was heated in an oil bath at 110° C. for 4hours. All the solvent was then removed within one hour. The reactionmixture was stirred at 110° C. in neat state for an additional 1 hour. Abeige solid material was obtained at room temperature, reactionproduct 1. The product was transferred into a 100 mL volumetric flask,rinsed and diluted with 30% sulfuric acid to form a light beige coloredsolution.

Two additional reaction products were prepared substantially accordingto the method described above except that the sulfonamide monomers werevaried as disclosed in Table 1.

TABLE 1 Molar Reaction Ratio Product Monomer 1 (M₁) Monomer 2 (M₂)(M₁:M₂) 1

polyethyleneglycoldiglycidyl ether 1:1 2

polyethyleneglycoldiglycidyl ether 1:1 3

polyethyleneglycoldiglycidyl ether 1:1

Example 2

To a 100 mL round bottom three-neck flask equipped with a condenser anda magnetic stirrer, 2.5 mmol benzenesulfonamide and 2.5 mmol1H-imidazole was added followed by addition of a solution of 5 mmolpoly(ethyleneglycol)diglycidyl ether (Mn 526) in 40 mL of ethanol. 5 mgK₂CO₃ was then added into the reaction mixture. The mixture was heatedin an oil bath at 110° C. for 4 hours. All of the solvent was removed at110° C. within one hour. The reaction mixture was kept at 110° C. inneat state for one additional hour. A slight orange sticky material wasobtained as the final product, reaction product 4. The product wastransferred into a 100 mL volumetric flask, rinsed and diluted with 10%sulfuric acid to form a light beige colored solution.

Six additional reaction products were prepared substantially accordingto the method described above except that the monomers were varied asdisclosed in Table 2.

TABLE 2 Re- action Monomer 1 Monomer 2 Monomer 3 Molar Ratio Product(M₁) (M₂) (M₃) (M₁:M₂:M₃) 4

1 H- imidazole polyethylene- glycoldiglycidyl ether 1:1:2 5

1 H- imidazole polyethylene- glycoldiglycidyl ether 1:1:2 6

1 H- imidazole 1,4-bis(oxiran-2- ylmethoxy)butane 1:1:2 7

2,5-dimethyl- 1H-imidazole polyethylene- glycoldiglycidyl ether 1:1:2 8

2-ethyl-1H- imidazole polyethylene- glycoldiglycidyl ether 1:1:2 9

2-amino- ethanol polyethylene- glycoldiglycidyl ether 1:1:2 10 

1-amino- propan-2-ol polyethylene- glycoldiglycidyl ether 1:1:2

Example 3

A plurality of copper electroplating baths were prepared by combining 75g/L copper as copper sulfate pentahydrate, 240 g/L sulfuric acid, 60 ppmchloride ion, 1 ppm of an accelerator and 1.5 g/L of a suppressor. Theaccelerator was bis(sodium-sulfopropyl)disulfide. The suppressor was anEO/PO copolymer having a weight average molecular weight of <5,000 andterminal hydroxyl groups. Each electroplating bath also contained one ofthe reaction products from Examples 1 and 2 in amounts of 0.5 ppm to 500ppm as shown in Table 3, in Example 4 below. The reaction products wereused without purification.

Example 4

Samples of a 3.2 mm thick of double-sided FR4 PCBs, 5 cm×9.5 cm, havinga plurality of through-holes were electroplated with copper in Haringcells using the copper electroplating baths of Example 3. The 3.2 mmthick samples had 0.3 mm diameter through-holes. The temperature of eachbath was 25° C. A current density of 2.15 A/dm² was applied to the 3.2mm samples for 80 minutes. The copper plated samples were analyzed todetermine the throwing power (“TP”) of the plating bath, and percentcracking according to the methods described below. Average number ofnodules for each sample was also determined by counting them usingfingertips across the sample surface and recording the nodules in agiven area of the plated surface.

Throwing power was calculated by determining the ratio of the averagethickness of the copper plated in the center of a through-hole comparedto the average thickness of the copper plated at the surface of the PCBsample. The throwing power is reported in Table 3 as a percentage.

The percent cracking was determined according to the industry standardprocedure, IPC-TM-650-2.6.8. Thermal Stress, Plated-Through Holes,published by IPC (Northbrook, Ill., USA), dated May, 2004, revision E.

The results showed that all of the samples tested had reduced noduleformation and some cracking was in the desired range of ≦10%. Althoughquality of % cracking varied for the levelers tested, all of the sampleshad % TP greater than 65% at optimized concentrations and the majorityof samples had % TP greater than 70%. Further, the number of nodulescounted on the samples was very low and at commercially acceptablelevels.

TABLE 3 Reaction product Leveler (ppm) % TP Nodules % Cracking 1 1 50 00 5 71 0 43 10 91 0 61 2 1 77 0 73 5 80 0 20 10 69 4 15 3 1 51 0 48 2 580 98 5 65 0 100 4 10 68 0 0 20 73 0 0 50 77 0 0 5 1 59 0 0 2 71 1 58 594 0 88 6 0.5 65 0 80 1 74 0 83 2 79 0 83 7 1 64 0 25 5 74 0 33 10 69 20 8 5 71 0 0 10 72 0 0 20 63 0 0 9 10 64 0 5 50 70 0 0 100 72 0 2.5 10100 61 0 0 200 64 0 0 500 69 0 0

What is claimed is:
 1. A method comprising: a) providing a substrate; b) providing a composition comprising one or more sources of copper ions, optionally one or more sources of tin ions, an electrolyte and a reaction product comprising: one or more sulfonamides or salts thereof, and one or more epoxides; c) contacting a substrate with the composition; d) applying a current to the substrate and the composition; and e) depositing a copper or copper/tin alloy on the substrate.
 2. The method of claim 1, wherein the substrate comprises a plurality of one or more of through-holes, trenches and vias. 